seen a number of posts like this on newsgroups and it is trivial
especially for developers who misuse the events of normal WinForms
First are those who use the
inefficient TextChanged event of the Windows Forms Textbox for
validating the user’s input. Second are those who use the LostFocus
and Leave events.
The ideal event to utilize in
validating inputs is the Validating event in combination with the
Validated event for after validation processing. This way, one can
just set the CausesValidation of the Cancel button to false in order to
suppress validation of any controls.